Functional fiber sheet

ABSTRACT

A functional sheet is coated with physically vapor-deposited film including titanium oxide and other metallic oxides for making the film transparent so color and pattern on the fiber sheet are visible, providing electric conductivity to the film, improving the productivity of vapor deposition and enabling selective blocking of infrared and ultraviolet radiation.

TECHNICAL FIELD OF THE INVENTION

This invention relates to functional fiber sheet coated with physicallyvapor-deposited film comprising titanium oxide and other metallicoxides.

RELATED ART

It is known that by forming metallic or metallic oxide thin film on thesurface of fiber sheet comprising synthetic fiber such as woven goods,knit goods, nonwoven fabric, through the use of physical vapordeposition methods such as vacuum vapor deposition, ion beam method,sputtering method, etc., various types of functions can be conferred onthe fiber sheet such as electric conductivity, heat-shielding, heatretention, dirt repellency, anti-bacterial properties, deodorizingproperties, and the like. However, when the fiber sheet surface iscoated with a vapor-deposited film of metal, for example, stainless,titanium, chromium, or copper and the like, color, pattern, etc. on thefiber sheet are hidden by the vapor-deposited film and present ametallic color, lack of variety from a fashion standpoint was a problem.On the one hand, when vapor-deposited film comprising metallic oxidessuch as titanium oxide, etc. is formed, because said oxides compriseordinary oxide containing oxygen in the minus two valence state, it waspossible to enable color and pattern and the like to become visible byadjusting film thickness so that vapor-deposited film was transparent;on the other hand, there were problems in that electric conductivity waspoor in comparison to metallic vapor-deposited film; heat-shieldingproperties were inferior as well, moreover, productivity decreased.

Further, formation of vapor-deposited film is known, having multilayerstructure comprising TiO₂, Ag and TiO₂ as the three layers,vapor-deposited film increasing visible light transmittance whileselectively blocking ultraviolet and infrared radiation; however,because this vapor-deposited film peels readily upon repeated washing,it was not practical, moreover, there were problems in that metaloxidized on use, properties deteriorated.

This invention, in functional fiber sheet obtained by coating fibersheet with physically vapor-deposited film, by changing the compositionof this physically vapor-deposited film, made the vapor-deposited filmtransparent so color and pattern on the fiber sheet became visible,furthermore, was able to provide functionality to the vapor-depositedfilm such as electric conductivity, infrared radiation blocking,ultraviolet radiation blocking, and the like, moreover, madeproductivity increase possible at the time of vapor-deposition.

SUMMARY OF THE INVENTION

Fiber sheet relating to this invention, in functional fiber sheetcomprising fiber sheet comprising synthetic fiber, one face or bothfaces thereof being coated with physically vapor-deposited filmcomprising metallic oxides, aforementioned metallic oxides characterizedas comprising a mixture of ordinary oxides as a main component,containing a small amount of oxides having a lower valence than theordinary oxides.

Synthetic fibers used in this invention comprise thermoplastic syntheticfibers used in usual knit and woven use, exemplified by polyester fiber,nylon fiber, acrylic fiber and polyimide fiber and the like. Inparticular, polyester fiber is preferred from the standpoint of lowmoisture content, ease in physical vapor deposition of metals andmetallic oxides, and superior durability of the vapor-deposited film.This synthetic fiber can be in either staple or filament form; staple orfilament is used without modification in the manufacture of nonwovenfabric, but when used as structural yarn for woven goods or knit goods,filament yarn such as monofilament yarn and multifilament yarn ispreferred.

In this invention, thin film comprising metallic oxides such as titaniumoxide is formed on one face or both faces of aforementioned fiber sheet,by physical vapor deposition methods such as vacuum vapor deposition,ion beam method, sputtering method, etc., preferred method issputtering. Aforementioned metallic oxides comprise ordinary oxidecontaining oxygen in the −2 valence state as principal substance, asmall amount of oxides having lower valence than the ordinary oxides asa secondary component, hereinafter termed lower oxides is mixed therein.For example, in the oxides of titanium, tetravalent oxide TiO₂ is knownas the ordinary oxide, as lower oxides, divalent oxide TiO and trivalentoxide Ti₂O₃ are known. Consequently, the vapor-deposited film oftitanium oxide is formed by a mixture of the aforementioned ordinaryvalence oxides (tetravalent oxides) and lower valence oxides (divalentor trivalent oxides).

In physical vapor deposition such as sputtering and the like, whilemetal is sputter-vaporized in a sealed chamber containing a slightamount of argon gas, it is oxidized by a small amount of oxygen suppliedto the chamber, and adsorbed on the fiber sheet, but when the amount ofoxygen supplied reaches the amount adequate for production of ordinaryoxide, only the ordinary oxide is produced, concurrently, surface of thetarget metal is oxidized to effect large reduction in the amount ofvaporized metal, productivity drops.

In contrast to this, when the amount of oxygen supplied is an amountless than that needed for production of ordinary oxides, aforementionedlower oxides are also produced concurrently with ordinary oxide, theseare adsorbed in the form of mixture on the fiber sheet, moreover,because the target surface is not oxidized, amount of vaporized metaldoes not decrease, drop in productivity is prevented. Consequently, byforming vapor-deposited film comprising the aforementioned mixture,moreover, by adjusting the thickness of the vapor-deposited film, itbecomes possible to provide electric conductivity, heat-shielding, andother functions to the vapor-deposited film while transparency ismaintained. Furthermore, in the aforementioned sputtering situation,productivity is improved to an even higher level by admixing a slightamount of nitrogen gas together with argon gas and oxygen.

In order to set the amount of oxygen supplied at an amount less thanthat needed for production of ordinary oxide, it is advantageous todetermine the unique brightness of light emitted by vaporized metal whenthe vaporized metal passes through the plasma generated at the time ofsputtering, for example, the luminance, and adjust the amount of oxygensupplied so this luminance is maintained at a constant level. Forexample, in the case where the metal is titanium, when titanium passesthrough plasma upon sputter vaporization, visible light at wavelength453 nm is emitted, in the absence of oxygen, the vaporization speedattains a maximum, the brightness is strongest; when excess oxygen issupplied, vaporization speed attains a minimum, brightness decreases aswell. Consequently, by adjusting the amount of oxygen supplied on thebasis of luminance, it becomes possible to control the amount of loweroxide. Further, it is possible to use any desired intensity indexcorrelated to luminance, instead of luminance itself.

Mixture content of oxides having valence lower than that ofaforementioned ordinary oxide, in other words, lower oxide, ispreferably 0.1˜20 wt % of the total oxides; when this mixture content isless than 0.1 wt %, functions such as electric conductivity andheat-shielding are not obtained, moreover, productivity is drasticallydecreased; in contrast, at more than 20 wt %, metallic color is evident,moreover, visible light transmittance is insufficient, fiber sheetattributes are lost. Further, thickness of the aforementioned physicallyvapor-deposited film is preferably 5˜500 nm, in particular, 30˜300 nm;at less than 5 nm, functions such as electric conductivity,heat-shielding, infrared radiation cuts, ultraviolet radiation cuts,etc. are not obtained, at greater than 500 nm, structural fibers, color,pattern, etc. of the fiber sheet are not visible, there are difficultiesin attaining practical use from a cost standpoint as well.

Further, transparency of the aforementioned physically vapor-depositedfilm is preferably 30% or more for visible light transmittance atwavelength 550 nm, at less than 30%, color and pattern on the surface ofthe fiber sheet [and] fibers are no longer visible, fiber sheetattributes are lost. Further, transmittance of infrared radiation andultraviolet radiation is fixed by the mixture content of the lowervalence oxides, but when infrared radiation cuts comprise the objective,it is preferable to set the mixture content on the high side andsuppress the infrared radiation transmittance to 70% or less atwavelength 1000 nm. Further, when ultraviolet radiation cuts comprisethe objective, it is preferable to set the aforementioned mixturecontent on the low side and suppress the ultraviolet radiationtransmittance to 50% or less at wavelength 400 nm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of sputtering device related toWorking Example 1.

FIG. 2 is a graph showing light transmittance of vapor-deposited film.

FIG. 3 is a graph showing light reflectivity of vapor-deposited film.

DETAILED DESCRIPTION OF THE INVENTION EXAMPLES OF THE INVENTION Example1

As fiber sheet, woven fabric using polyester fiber multifilament yarn aswarp and weft is used, transparent coating of titanium oxide is formedon its surface by sputtering, having thickness of 5˜500 nm, preferably30˜300 nm.

FIG. 1 shows one example of a sputtering device, sealable chamber 10 isdivided by horizontal divider 11 into sputtering chamber 12 below andfabric chamber 13 above, in the middle of sputtering chamber 12 below,flat plate target 14 comprising titanium is fixed on target source 15located in mid-air, target 14 is cooled from its bottom face by coldwater passing through this target source 15. Anode 16 is affixedhorizontally at the left and right above this target 14, direct currentvoltage of 200˜1000 V is impressed by means of direct current powersource 17 between this anode 16 and target 14.

Water-cooled cylinder 18 is affixed horizontally above aforementionedanode 13, and moreover, rotates freely, above this to the left, fibersheet sending shaft 19, further, above and to the right, fiber sheet Fwinding shaft 20 are respectively horizontally affixed, moreover, theserotate freely. Thus, pre-process fiber sheet F wrapped around sendingshaft 19 is pulled out, wrapped around aforementioned water-cooledcylinder 18 through guide roller 21 at upper left, and wound on windingshaft 20 through guide roller 22 at upper right. Further, vacuum pump23, argon gas supply gas bomb 24, and oxygen gas supply gas bomb 25 arerespectively connected to aforementioned chamber 10.

In the aforementioned device, sending shaft 19, winding shaft 20, andwater-cooled cylinder 18 are rotated, fabric F is sent at a fixed speedin counterclockwise direction while being cooled on water-cooledcylinder 14, surface temperature of fabric F is maintained at 60° C. orlower. On the other hand, vacuum pump 23 is driven to reduce internalpressure in chamber 10 to about 1.3×10⁻³ Pa, next, argon gas from argongas supply gas bomb 24 and oxygen from oxygen gas supply gas bomb 25 arerespectively introduced to adjust the internal pressure of chamber 10 toabout 1×10⁻² Pa, sputtering is implemented thereafter, titanium emittedfrom target 14 is reacted with oxygen to form titanium oxide, this isallowed to adhere on aforementioned fiber sheet F, transparentphysically vapor-deposited film is formed.

At this time, sputtering is implemented while brightness of vaporizedtitanium passing through plasma above target 14 is observed; during thistime, by adjusting the amount of oxygen sent from oxygen gas supply gasbomb 25 to chamber 10, the luminance of aforementioned vaporizedtitanium or any desired intensity index correlated to luminance iscontrolled at a fixed level determined by tests beforehand; by thismeans titanium oxide comprises [a mixture of] ordinary oxides and loweroxides, the mixture is formed wherein the amount of lower oxide to thetotal amount of metallic oxides is 0.1˜20 wt %, to be adsorbed on fibersheet F. Further, traveling speed of fiber sheet F is adjusted so thatphysically vapor-deposited film comprising aforementioned titanium oxidehas thickness of 5˜500 nm.

In the aforementioned Working Example, as the amount of oxygen suppliedto chamber 10 is set higher, further, as the setting for luminance isset lower, there is increase in ordinary oxide and decrease in loweroxide, transparency of the physically vapor-deposited film increases. Onthe other hand, as the amount of oxygen supplied is set lower, further,as the setting for luminance (intensity) is set higher, there isdecrease in ordinary oxide and increase in lower oxide, transparency ofthe physically vapor-deposited film decreases, metallic color becomesstronger. Furthermore, by the aforementioned adjustment of luminance, itbecomes possible to maintain visible light transmittance at 20% or more,while infrared radiation transmittance or ultraviolet radiationtransmittance is suppressed at 70% or less.

By using warp-knit fabric comprising polyester fiber multifilament yarnas the aforementioned fiber sheet, and other than that, implementingsputtering just as described above, fiber sheet was obtained that hadelectric conductivity and heat-shielding properties, moreover, wasprovided with the attributes of warp-knit fabric, had visible lighttransmittance of 30% or more, infrared radiation transmittance orultraviolet radiation transmittance of 70% or less.

Further, by using spun-bonded nonwoven fabric comprising polyesterfilament as the afore-mentioned fiber sheet, and other than that,implementing sputtering just as described above, fiber sheet wasobtained that had electric conductivity and heat-shielding properties,moreover, was provided with the attributes of spun-bonded nonwovenfabric, had visible light transmittance of 30% or more, infraredradiation transmittance or ultraviolet radiation transmittance of 70% orless.

Example 2

By using sputtering device in FIG. 1, implementing sputtering on oneface of fiber sheet comprising woven goods, knit goods or nonwovenfabric, etc., to form aforementioned physically vapor-deposited film,thereafter removing aforementioned fiber sheet temporarily, thereafterreversing the front and back and reattaching to the sputtering device,thereafter implementing sputtering on the other face identically asaforementioned, fiber sheet is obtained, having aforementionedphysically vapor-deposited film on both front and back faces, havingvisible light transmittance of 30% or more, infrared radiationtransmittance or ultraviolet radiation transmittance of 70% or less,moreover, being provided with attributes of fiber sheet, color andpattern being visible thereon, having no metallic color.

Example 3

In the aforementioned sealed chamber, 2 sets of vapor deposition devicesare set up in rows, sputtering is implemented continuously on both frontand back faces to form the aforementioned physically vapor-depositedfilm. For example, No. 1 water-cooled cylinder and No. 2 water-cooledcylinder are set up in parallel to the left and right of center in thesealed chamber, No. 1 water-cooled cylinder on the left is rotated incounterclockwise direction, No. 2 water-cooled cylinder on the right isrotated in clockwise direction, respectively; sputtering is implementedby wrapping fiber sheet from the left so that its back face comes incontact with the lower half of No. 1 water-cooled cylinder, next, [sheetis] led to top right of No. 2 water-cooled cylinder, sputtering isimplemented by wrapping fiber sheet from the right so that its frontface comes in contact with the lower half of this No. 2 water-cooledcylinder.

As fiber sheet F in Working Example 1, 190-count taffeta using polyestermultifilament yarn in warp and weft was used, transparent physicallyvapor-deposited film of titanium oxide was formed on one face thereof bysputtering. As oxygen supply control, “Dual Magnetron Cathode PlasmaEmission Monitor” (“von Alden”, Germany) was used; monochromatic light(wavelength 453 nm) unique to metallic titanium was taken out withcollimator to determine luminance, aforementioned luminance wasexpressed as intensity, where luminance at zero oxygen supply was 100,luminance at excess oxygen supply was 10; Test Sample A was obtainedwhen this intensity was set at 50. Also, Test Sample B was obtained whenintensity was set at 30.

The compositions of physically vapor-deposited film for Test Sample Aand Test Sample B were analyzed by X-ray photoelectronspectrophotometry. As the analytical device, SSX-100 Model X-rayPhotoelectron Spectrophotometer (SSI Co.) was used. Upon analysis byusing monochromatic AlKα (100 W) as the x-ray source, in Test Sample Aat intensity 50, about 5% trivalent lower oxide Ti₂O₃ was also presentin tetravalent ordinary oxide. Further, in Test Sample B at intensity30, this vapor-deposited film was formed almost completely withtetravalent ordinary oxide TiO₂. Ratio of titanium and oxygen in thevapor-deposited film was 1/2.15 in Test Sample A, 1/2.39 in Test SampleB. Further, external appearances were compared for the aforementionedTest Sample A and B, the results, together with the aforementionedanalytical results are shown in Table 1 below.

TABLE 1 Test Sample A Test Sample B Intensity 50 30 Thickness of vapor-50 50 deposited film (μm) External appearance Colorless transparentColorless transparent Titanium/oxygen 1/2.15 1/2.39 (atom ratio) Lowvalence oxide  5%  0% content

Vapor-deposited film of aforementioned titanium oxide was formed ontransparent film having thickness of 50 μm, comprising polyethyleneterephthalate, to measure the electric conductivity and lighttransmittance of the aforementioned vapor-deposited film. At this time,Test Samples 1˜6 were prepared by changing intensity in 6 steps, 70, 60,50, 40, 30, 20. Then electric conductivity, light transmittance atwavelength 400˜1000 nm and light reflectivity were respectively measuredfor these Test Samples 1˜6. Electric conductivity is shown in Table 2,light transmittance in FIG. 2, light reflectivity in FIG. 3,respectively.

TABLE 2 Test Sample No. 1 2 3 4 5 6 Intensity 70 60 50 40 30 20 Electric8 × 10³ 1 × 10⁴ 7 × 10⁴ 4 × 10⁷ — — conductivity (Ω/cm)

As shown in aforementioned Table 2, when electric conductivity iscompared in terms of resistance values, Test Sample 1 having intensity70, containing the most lower oxide, has the lowest resistance value; asthe amount of lower oxide decreases, resistance values decrease in theorder of Test Sample 2 having intensity 60, Test Sample 3 havingintensity 50, Test Sample 4 having intensity 40; resistance values couldnot be measured for Test Sample 5 having intensity 30 and Test Sample 6having intensity 20, electric conductivity was essentially zero.

Further, in light transmittance, as shown in FIG. 2, Test Sample 4˜6having low intensity had high transmittance, transparency increased, incontrast, in Test Sample 1˜3 having high intensity, transmittancedecreased, there was a tendency for external appearance to present ametallic color. Further, in Test Sample 6 having intensity 20,transmittance was 60% or more in the entire range including ultravioletradiation to infrared radiation, from wavelength 400 mm to 1000 nm. InTest Sample 5 having intensity 30, ultraviolet radiation transmittanceat wavelength 400 nm was less than 50%, but for the remaining visiblelight and infrared radiation, transmittance was 50˜70%. In Test Sample 4having intensity 40, infrared radiation transmittance was lower than70%, although tendency somewhat similar to Test Sample 3 was displayed.

Further, in Test Sample 3 having intensity 50, visible lighttransmittance at wavelength 550 nm was about 50%, for ultravioletradiation at wavelength 400 nm, about 45%, for infrared radiation atwavelength 1000 nm, about 43%. Further, in Test Sample 2 havingintensity 60, about equal transmittance was observed in the range of40˜45% from ultraviolet radiation at wavelength 400 nm to visible lightat wavelength 700 nm; transmittance gradually decreased beyond 700 nm,and was about 35% at infrared radiation wavelength 1000 nm. Further, inTest Sample 1 having intensity 70, transmittance decreases graduallyfrom about 37% to 30%, from ultraviolet radiation at wavelength 400 toinfrared radiation at wavelength 1000 nm, Furthermore, lighttransmittance of the aforementioned film itself was about 85% atwavelength 400 nm, about 88% at wavelength 550 nm, about 89% atwavelength 1000 nm; there was a very slight upward trend to the right.

On the other hand, light reflectivity, as shown in FIG. 3, had asomewhat downward slope to the right in Test Sample 4˜6 having lowintensity, in Test Sample 1˜3 having high intensity, a tendency toward asomewhat upward slope to the right was observed. However, Test Sample 6having intensity 20 showed the highest reflectivity of about 28% atwavelength 500˜600 nm in the visible light range, there was a suddendrop on the ultraviolet radiation side, a gradual decrease on theinfrared radiation side, the curve had a mountain shape. Also, in TestSample 5 having intensity 30 and Test Sample 4 having intensity 40, thedownward slopes to the right were more or less similar, reflectivity atwavelength 400 nm was about 33%, reflectivity at wavelength 1000 nm was17˜19%.

Further, Test Sample 3 having intensity 50 showed the lowestreflectivity of about 19% at wavelength 500˜600 [nm] in the visiblelight range, there was a gradual increase toward wavelength 400 nm and1000 nm to about 22˜23%. Further, Test Sample 2 having intensity 60showed more or less uniform reflectivity of 16˜17% at wavelength 550 nmor less, there was a gradual increase to reflectivity of 26% atwavelength 1000 nm. Further, in Test Sample 1 having intensity 70,reflectivity increased more or less linearly following the wavelength,to about 18% at wavelength 400 nm, about 37% at wavelength 1000 nm.Furthermore, reflectivity of the film itself showed a constant value ofsome 11% in the entire wavelength range of 400˜1000 nm.

As described above, because in functional fiber sheet relating to thisinvention, metallic oxides constituting its physically vapor-depositedfilm comprise not only ordinary oxide but also contain a small amount oflower oxide, by setting the amount of lower oxide in the amount ofmixture, it is possible to maintain transparency of the vapor-depositedfilm so color and pattern of the fiber sheet are visible, fashionabilityand attributes of the fiber sheet are maintained, at the same time,functionality is provided such as electric conductivity, heat-shielding,infrared radiation blocking, ultraviolet radiation blocking, dirtrepellency, anti-bacterial properties and corrosion resistance and thelike, by means of the vapor-deposited film; moreover, productivity issatisfactory, and there is superior washability and peel resistance.Consequently, the aforementioned functional fiber sheet is very suitablefor uses such as industrial materials, e.g. mesh screen and filter andthe like, insect netting, house-wrapping material, also, outdoor tent,umbrella, indoor decorative wall panel material, ceiling material, andinterior material and the like, having superior corrosion resistance andwashability as well, being able to satisfy fashionability and variousfunctionalities.

While three examples of the present invention has been shown anddescribed, it is to be understood that many changes and modificationsmay be made thereunto without departing from the spirit and scope of theinvention as defined in the appended claims.

1. A functional fiber sheet comprising synthetic fiber, at least oneface thereof being coated with a physically vapor-deposited transparentfilm comprising metallic oxides, wherein said metallic oxides comprise amixture of an ordinary oxide as a main component and a small amount ofoxides having a lower valence than said ordinary oxide as a secondarycomponent, wherein said metallic oxide is titanium oxide, its ordinaryoxide being a tetravalent oxide and said lower valence oxides beingdivalent or trivalent oxides, and the amount of lower valence oxides tothe total amount of the metallic oxides is 0.1 to 20 wt %.
 2. Thefunctional fiber sheet described in claim 1 wherein the thickness ofsaid physically vapor-deposited film is 5 to 500 nm.
 3. The functionalfiber sheet as set forth in claim 1 wherein the synthetic fibercomprises synthetic fiber used in usual knit and woven use.
 4. Thefunctional fiber sheet as set forth in claim 1 wherein the syntheticfiber comprises polyester fiber, nylon fiber, acrylic fiber or polyimidefiber.
 5. A method for manufacturing a functional fiber sheet comprisingthe steps of: forming a physically vapor-deposited transparent film ofmetallic oxides on a fiber sheet through a physical vapor depositionprocess; forming an ordinary oxide as a main component of the metallicoxides of the physically vapor-deposited transparent film by increasingthe amount of oxygen to be supplied during the physical vapor depositionprocess; and forming a small amount of oxides having a lower valencethan said ordinary oxide as a secondary component of the metallic oxidesby lowering the amount of oxygen to be supplied to the physical vapordeposition process, wherein said metallic oxide is titanium oxide, itsordinary oxide being a tetravalent oxide and said lower valence oxidesbeing divalent or trivalent oxides, and the amount of lower valenceoxides to the total amount of the metallic oxides is 0.1 to 20 wt %.